The present invention pertains to liquid compositions of matter useful as herbicides and to liquid concentrates from which liquid herbicides may be prepared, wherein the active herbicidal ingredient is a salt of N-phosphonomethyl glycine, which is commonly referred to as glyphosate by those skilled in this art. Owing to the fact that glyphosate in its acid form has a low solubility in water, those skilled in the art who produce and/or use formulations containing glyphosate have found it beneficial to employ a water-soluble glyphosate salt in their formulations in order to achieve higher levels of glyphosate effectively dissolved in the solutions. This is regarded as being common knowledge in the art, and salts typically employed are the amine salts of glyphosate, including without limitation the mono-iso-propylamine salt of glyphosate, alkanolamine salts of glyphosate, the alkali and/or alkaline earth metal salts of glyphosate, and mixtures comprising any of the foregoing.
In a general sense, it is desirable to provide concentrates which contain one or more salts of glyphosate in as high a concentration as possible because the higher the concentration, the more active ingredient is contained in a given volume, which reduces shipping costs and enables large volumes of final solutions to be prepared from small volumes of concentrate by mere addition of water. Thus, it is desirable to increase the maximum level of glyphosate loading possible to successfully formulate in a commercially-viable product.
One current commercial glyphosate formulation is the mono-iso-propylamine (“IPA”) salt in loaded at 480 g/L active ingredient, which is approximately 360 g/L glyphosate (acid form) equivalent. U.S. Pat. No. 5,668,085 discloses that mono-iso-propylamine glyphosate solutions are easily prepared containing 250-400 g/L of glyphosate acid equivalent.
European Patent EP 1 133 233 B1 (WO 00030452 A1) discloses an adjuvant system compatible with the mono-ethanolamine (“MEA”) salt of glyphosate. Table 1 of this patent shows how the cloud point decreases with increasing surfactant concentration. The patent further states the commonly-held belief that to maintain acceptable cloud point when raising the concentration of glyphosate, the surfactant concentration must be reduced. The cloud point is a measure of the maximum temperature at which a given aqueous composition containing a surfactant and a salt of glyphosate at defined concentrations forms a single-phase solution. Above the cloud point, the surfactant separates from the solution, initially as a hazy or cloudy dispersion, and, upon standing, as a distinct phase generally rising to the surface of the solution. (Cloud point of a composition is normally determined by heating the composition until the solution becomes cloudy, and then allowing the composition to cool, with agitation, while its temperature is continuously monitored. A temperature reading taken when the solution clears is a measure of cloud point.) European Patent EP 0 999 749 B1 discloses high-load ammonium glyphosate. The publications WO 00/30451 and EP1438896A1 disclose compositions containing the MEA salt of glyphosate.
The object of this invention is to provide commercially viable products of very high loaded glyphosate formulations. This invention pertains to IPA salts of glyphosate.